This HTML5 app can be used to explore the properties of simple geometric mappings. Four types of isometries (transformations which preserve the lengths of line segments and the measures of angles) can be selected:
The type of transformation is specified in the selection field at the top right. If you click with the mouse on the button "New sketch", all objects of the previous drawing and their images will be deleted. In the selection field below you can define what to draw next. After a mouse click on "Add" a new object (a point, a line, a ray, a line segment, a circle, a triangle or a quadrilateral) will appear in red color. With a mouse click you can select an object (recognizable by the red color). This object can be varied by dragging the mouse with pressed mouse button. The same is valid for the axis of symmetry, the point of inversion, the translation arrow or the rotation arrow. The effect of the "Delete" button also refers to the object marked in red. In the checkbox "Image" you can decide whether image objects should be drawn or not. The color of the image objects is blue.